1. Field of the Invention
The present invention relates to a method and apparatus for transmitting and receiving group resource deallocation information in a communication system. More particularly, the present invention relates to a method and apparatus for transmitting and receiving group resource deallocation information in a communication system using a group resource allocation scheme.
2. Description of the Related Art
Next-generation communication systems have evolved to offer various high-speed, high-capacity services to Mobile Stations (MSs). Typical examples of next-generation communication systems include an Institute of Electrical and Electronics Engineers (IEEE) 802.16 communication system and a Mobile Worldwide Interoperability for Microwave Access (WiMAX) communication system. The Mobile WiMAX communication system is a communication system based on the IEEE 802.16 communication system.
The IEEE 802.16m communication system is an example of an IEEE 802.16 communication system. The IEEE 802.16m communication system uses both an individual resource allocation scheme and a group resource allocation scheme as resource allocation schemes. The individual resource allocation scheme allocates resources to MSs on an individual basis. The group resource allocation scheme groups multiple MSs into a group and allocates resources to MSs in the group. For sake of convenience, resource allocation information for the resources allocated using the individual resource allocation scheme is referred to as ‘individual resource allocation information’, and when the resources allocated using the individual resource allocation scheme are deallocated, the resource deallocation information is referred to as ‘individual resource deallocation information’. Similarly, resource allocation information for the resources allocated using the group resource allocation scheme is referred to as ‘group resource allocation information’, and when the resources allocated using the group resource allocation scheme are deallocated, the resource deallocation information is referred to as ‘group resource deallocation information’.
Related methods for transmitting the individual resource allocation information, the individual resource deallocation information, the group resource allocation information, and the group resource deallocation information will be described below.
First, related methods of transmitting the individual resource allocation information and the individual resource deallocation information will be described below.
After allocating resources to each of a plurality of MSs, a Base Station (BS) sends the MSs a resource allocation message that includes an Information Element (IE) indicating individual resource allocation information for the allocated resources, i.e., an individual resource allocation IE. For sake of convenience, the resource allocation message including the individual resource allocation IE will be referred to as an ‘individual resource allocation message’, and the individual resource allocation message may be realized as, for example, a MAP message. In contrast, the BS deallocates the resources allocated to a particular MS among the MSs that have already been allocated resources, and then sends the MS a resource deallocation message that includes an IE indicating individual resource deallocation information for the deallocated resources, i.e., an individual resource deallocation IE. For sake of convenience, the resource deallocation message including the individual resource deallocation IE will be referred to as an ‘individual resource deallocation message’, and the individual resource deallocation message may also be realized as, for example, a MAP message.
Second, related methods of transmitting the group resource allocation information and the group resource deallocation information will be described below.
The BS selects MSs according to a service type or a Modulation and Coding Scheme (MCS) and groups the selected MSs. The BS generates a group resource allocation IE with group resource allocation information for MSs in the group, and sends a resource allocation message including the group resource allocation IE to the MSs in the group. For sake of convenience, the resource allocation message including the group resource allocation IE will be referred to as a ‘group resource allocation message’, and the group resource allocation message may be realized as, for example, a MAP message. Because the group resource allocation IE includes group resource allocation information for multiple MSs in the group, an MCS level to be applied to the group resource allocation IE is determined based on the MS with the lowest required MCS level among the MSs that will receive the group resource allocation IE. In addition, since all the MSs in the group should successfully receive the group resource allocation IE, transmit power to be applied to the group resource allocation IE should be set relatively high. Furthermore, since the group resource allocation IE includes group resource allocation information for multiple MSs, its length is relatively long.
In contrast, the BS deallocates the resources allocated to a particular MS among the MSs that have already been allocated resources, and then sends multiple MSs in the group a resource deallocation message that includes an IE indicating group resource deallocation information indicating the deallocation of the resources allocated to the particular MS, i.e., a group resource deallocation IE. For sake of convenience, the resource deallocation message including the group resource deallocation IE will be referred to as a ‘group resource deallocation message’, and the group resource deallocation message may also be realized as, for example, a MAP message. Similarly, even for the group resource deallocation IE, an MCS level to be applied is determined based on the MS with the lowest required MCS level among the MSs in the group. Transmit power to be applied is set relatively high, and its length is also relatively long.
As described above, regarding the group resource deallocation IE, its length is long, the lowest MCS level among the required MCS levels of MSs that will receive the group resource deallocation IE should be applied, and relatively high transmit power should be used. Hence, many resources are consumed for transmission/reception of the group resource deallocation IE, which increases system overhead. Therefore, there is a need to reduce the amount of required resources for transmission and reception of a group resource deallocation IE in the IEEE 802.16m communication system.